Home / Examples / Magnetic Analysis (Luvens, Transient Analysis) / Example 6: Torque Analysis of Outer Rotor Motor

Example 6: Torque Analysis of Outer Rotor Motor

General

Torque characteristics of an outer rotor motor for a drone is analyzed when electricity is applied.
The model is a permanent magnet synchronous motor with magnets arragned on the outer rotor.
The analysis is coupled with the external circuit.
The torque and the magnetic flux density are solved.
Unless specified in the list below, the default conditions will be applied.

Analysis Conditions

Item	Settings
Analysis Space	2D
Thickness in Depth Direction	6 [mm]
Unit	mm
Solver	Magnetic Analysis [Luvens]
Analysis Type	Transient Analysis
Options	Select External Circuit Coupling. Select Rotating Machinery.

The Rotating Machinery tab is set as follows.

Tab

Setting Item

Settings

Rotating Machinery

Rotational Movement

Select Constant Velocity

Number of Rotations: 7200 [r/min]

Rotor’s Initial Rotation Position: 0 [deg]

Number of Sliding Mesh Divisions

Circumferential Division Angle: 1.0 [deg]

Rotational Quantity per Step: 1 [mesh]

Number of Sliding Mesh Layers: 3

External circuit is as follows.

3-phase AC voltage of 840 Hz is applied.

Set the Mesh Tab as follows.

Tab

Setting Item

Settings

Mesh

Meshing Setup

Automatically set the general mesh size: Deselect

General Mesh Size: 0.4 [mm]

Ambient Air Creation

Select Create ambient air automatically

Ambient Air Scale: 1.2

The Transient Analysis tab is set up as follows.

The umber of calculation steps is 180, circumferential division angle is 1.0 [deg], and rotational quantity per step is 1 [mesh]. The rotation up to 180 deg (=180*1.0*1) is analyzed.

Tab

Setting Item

Settings

Transient Analysis

Timestep

Automatic

Table

Number	Calculation Steps	Output Interval
1	180	1

Graphical Objects

A stator core and coils are placed in the center. A rotor core and magnets are placed around them.

The motor has 14 poles.

This is a 2D model analysis.

[Create ambient air automatically] is selected.

Body Attributes and Materials

Body Number/Type	Body Attribute Name	Material Name
4/Sheet	Mag1	mag
6/Sheet	Mag1	mag
8/Sheet	Mag1	mag
10/Sheet	Mag1	mag
12/Sheet	Mag1	mag
14/Sheet	Mag1	mag
16/Sheet	Mag1	mag
5/Sheet	Mag2	mag
7/Sheet	Mag2	mag
9/Sheet	Mag2	mag
11/Sheet	Mag2	mag
13/Sheet	Mag2	mag
15/Sheet	Mag2	mag
17/Sheet	Mag2	mag
0/Sheet	Rotor	core
37/Sheet	Stator	core
40/Sheet	U1-	Cu
42/Sheet	U1-	Cu
51/Sheet	U1-	Cu
53/Sheet	U1-	Cu
39/Sheet	U1+	Cu
41/Sheet	U1+	Cu
43/Sheet	U1+	Cu
52/Sheet	U1+	Cu
44/Sheet	V1-	Cu
46/Sheet	V1-	Cu
55/Sheet	V1-	Cu
57/Sheet	V1-	Cu
45/Sheet	V1+	Cu
47/Sheet	V1+	Cu
54/Sheet	V1+	Cu
56/Sheet	V1+	Cu
48/Sheet	W1-	Cu
50/Sheet	W1-	Cu
59/Sheet	W1-	Cu
61/Sheet	W1-	Cu
38/Sheet	W1+	Cu
49/Sheet	W1+	Cu
58/Sheet	W1+	Cu
60/Sheet	W1+	Cu

The body attribute is set up as follows.

Body Attribute Name	Tab	Settings
Mag1	Direction	Direction Type: Centripetal Direction Direction: Outward
Mag1	Stator/Rotor/Air	Rotor
Mag2	Direction	Direction Type: Centripetal direction Inward
Mag2	Stator/Rotor/Air	Rotor
Rotor	Stator/Rotor/Air	Rotor
Stator	Stator/Rotor/Air	Stator
U1-	Current	Waveform: External Circuit Coupling Coil Name on the Circuit: U1 Turns: 35 [Turns] Direction: - Y Direction
U1-	Stator/Rotor/Air	Stator
U1+	Current	Waveform: External Circuit Coupling Coil name on the circuit: U1 Turns: 35[Turns] Direction: +Y Direction
U1+	Stator/Rotor/Air	Stator
V1-	Current	Waveform: External Circuit Coupling Coil Name on the Circuit: V1 Turns: 35 [Turns] Direction: - Y Direction
V1-	Stator/Rotor/Air	Stator
V1+	Current	Waveform: External Circuit Coupling Coil name on the circuit: V1 Turns: 35 [Turns] Direction: +Y Direction
V1+	Stator/Rotor/Air	Stator
W1-	Current	Waveform: External Circuit Coupling Coil Name on the Circuit: W1 Turns: 35 [Turns] Direction: - Y Direction
W1-	Stator/Rotor/Air	Stator
W1+	Current	Waveform: External Circuit Coupling Coil name on the circuit: W1 Turns: 35 [Turns] Direction: +Y Direction
W1+	Stator/Rotor/Air	Stator

The material properties are set as follows.

Material Name

Tab

Properties

Conductivity

Conductivity Type: Conductor

Conductivity: 5.977x107 [S/m]

mag

Permeability

Material Type: Permanent Magnet

Magnet

Magnetization Characteristic Type: Linear

Magnetization Strength: 1.25

Relative Permeability: 1.05

core

Permeability

Magnetization Characteristic Type: Select B-H curve

B-H Curve Table

Magnetic Field [A/m]	Magnetic Flux Density [T]
0	0
58	0.42
90	0.8
180	1.19
380	1.37
1100	1.48
2000	1.55
3000	1.608
11000	1.81
20000	1.91

Results

The distribution of the magnetic flux density at the rotation angle of 0 [deg] is shown below.

The torque waveform is shown as below. It is output to "Torque [N*m]" of the result table.

Transient state becomes steady at around 50 [deg].